A drive force distribution method and a drive force distribution control device is provided for a front and rear wheel drive vehicle provided with a drive force distribution device that controls a distribution of a drive force generated by a drive force source to main drive wheels and auxiliary drive wheels. A present distribution of the drive force to an auxiliary drive wheel side is increased by a first predetermined amount upon determining the rotational speed difference between the rotational speeds of the main drive wheels and the auxiliary drive wheels has been determined to not be smaller than a predetermined rotational speed difference. The present distribution of the drive force to the auxiliary drive wheel side is reduced by a second predetermined amount when the rotational speed difference has been determined to be smaller than the predetermined rotational speed difference.

A drive force control system for a vehicle configured to allow a driver to find out a steering angle at which a wheel grips a road surface. In the vehicle, a torque distribution ratio to a pair of wheels turned by a steering wheel and another pair of wheels is changeable. A controller restricts a control to change the torque distribution ratio in the event of a slip of the pair of wheels, if a steering angle of the pair of wheels is changed to allow the pair of wheels to grip a road surface.

The controller is programmed to perform first control that controls a driving force distributor such as to decrease a distribution rate upon satisfaction of a predetermined condition that a frequency of at least one rotation fluctuation of an output member of the drive system, a main drive wheel and a sub drive wheel is within a predetermined area, compared with the distribution rate upon non-satisfaction of the predetermined condition.

A four-wheel drive vehicle comprises: main drive wheels and sub-drive wheels; a first input rotating member; a first output rotating member; a second input rotating member; a second output rotating member; a first dog clutch; a second dog clutch; a synchromesh mechanism. In the case of canceling a disconnect state in which the power transmitting member interrupts power transmission from the drive power source and the sub-drive wheels, the control device controls an engagement torque of the coupling to a preset first torque and operates the synchromesh mechanism to engage the first dog clutch when it is determined that the rotation speeds are synchronized between the second input rotating member and the second output rotating member, and controls the engagement torque of the coupling to a second torque smaller than the first torque to engage the second dog clutch when it is determined that the first dog clutch is engaged.

A drive force control system for a vehicle configured to allow a driver to find out a steering angle at which a wheel grips a road surface. In the vehicle, a torque distribution ratio to a pair of wheels turned by a steering wheel and another pair of wheels is changeable. A controller restricts a control to change the torque distribution ratio in the event of a slip of the pair of wheels, if a steering angle of the pair of wheels is changed to allow the pair of wheels to grip a road surface.

A utility vehicle includes: a power unit that outputs drive power; a drive shaft that receives the drive power transmitted from the power unit; a front axle that receives the drive power transmitted from the drive shaft; a right front wheel connected to the front axle; a left front wheel connected to the front axle; a right clutch configured to disable power transmission from the drive shaft to the right front wheel; a left clutch configured to disable power transmission from the drive shaft to the left front wheel; a clutch actuator that actuates the left clutch and the right clutch; and a controller that controls the clutch actuator.

A vehicle includes a first axle temporary driven by a motor, a second axle permanently connected to the motor via a propeller shaft, and a sub-shaft that connects the propeller shaft and the first axle. A control system for a connection between the motor and the first axle includes a first clutch between the propeller shaft and the sub-shaft, a second clutch between the sub-shaft and the first axle. The first clutch is controlled to continue applying a synchronous torque until the second clutch is determined to be connected. The second clutch is controlled to be connected in response to a determination that the second clutch is connectable.

A vehicle system comprises an engine driving a vehicle, a front wheel and a rear wheel, a suspension device with an attachment portion to a vehicle body which is located at a higher level than a center axis of the rear wheel, an electromagnetic coupling to distribute a torque of the engine to the front wheel and the rear wheel, a steering wheel to be operated by a driver, a steering angle sensor to detect a steering angle corresponding to operation of the steering wheel, and a controller to control the engine and the electromagnetic coupling. The controller is configured to control the electromagnetic coupling such that the torque distributed to the rear wheel is decreased in accordance with returning operation of the steering wheel which is detected by the steering angle sensor.

A method for operating a drivetrain of a motor vehicle comprising an engageable and disengageable four-wheel drive and at least two intermeshing gears, in which the four-wheel drive is switched off by the opening of at least one clutch of the drivetrain, wherein a change of engagement of the gears resulting from the switching off is actively braked by an electric machine of the drivetrain.

A drive train for a hybrid vehicle, in particular for a temporarily four-wheel-driven motor vehicle, wherein the drive train comprises a first partial drive train assigned to a primary axle and a second partial drive train assigned to a secondary axle, and wherein the first partial drive train comprises a first drive unit configured as an internal combustion engine and a second drive unit configured as an electric machine and a change transmission, is refined in that the hybrid drive train is inexpensive to produce, has low CO2 emissions in operation, and may be used in a drive train of a temporarily four-wheel-driven motor vehicle. This is achieved in that change transmission comprises an input shaft and an output shaft, wherein the first drive unit is coupled to the primary axle via the change transmission, and wherein the second drive unit is coupled to the primary axle via the input or output shaft of the change transmission, and wherein the drive train furthermore comprises a clutch arrangement, wherein the secondary axle can be coupled in a driving manner to the primary axle by means of the clutch arrangement.